Musculature of the crus and pes of the African elephant (Loxodonta africana): insight into semiplantigrade limb architecture.

The limbs of elephants are designed to support the weight of the largest terrestrial animal, and they display unique morphological peculiarities among mammals. In this article we provide a new and detailed anatomical description of the muscles of the lower hindlimb in African elephants (Loxodonta africana), and we place our observations into a comparative anatomical as well as a functional morphological context. At the cranial aspect of the shank (crus) and the foot (pes), the flexors of the tarsal joint and the extensors of the toes form a flat muscular plate covering the skeletal elements. Caudal to the tibia and the fibula the Musculus (M.) soleus is strongly developed, whereas the M. gastrocnemius and the M. flexor digitorum superficialis are thin. Small flexors, adductors, and abductors of the toes are present. The M. tibialis caudalis as well as the Mm. fibularis longus and brevis mainly support the tarsal joint. The design of the muscular structures matches the specific requirements of heavy-weight bearing as well as of proboscidean limb posture and locomotion patterns.